A conventional flush valve of a plumbing system as used for flushing a toilet or urinal as shown in FIG. 1 includes: a diaphragm valve F formed in a central portion of a valve body communicated with an inlet pipe I for supplying water W therein, a solenoid S normally closing a valve opening V and operatively opened by a controller having a sensor A when detecting the presence of a person using the toilet or urinal for discharging flush water from the drain pipe D having a listed atmospheric vacuum breaker U mounted therein.
Upon opening of the solenoid valve S, the water W will flow through an orifice O formed in the diaphragm valve F, a valve opening V, and a central opening C in a stem T of the diaphragm valve F to be finally drained through the drain pipe D. The diaphragm stem T is reciprocatively moved and guided in a central hole H recessed in a central body portion, having a sealing ring R retained on the stem T for water sealing.
However, the conventional flush valve of FIG. 1 has the following drawbacks:
1. The sealing ring or O-ring R on the stem T may be easily worn to cause water leakage through the inside wall of the recessed hole H as indicated by dotted line L of FIG. 1 even if the solenoid valve S is normally closed, thereby wasting water and requiring frequent repair and maintenance for the flush valve. PA0 2. The top cap or cover E is merely provided for mounting the solenoid S, the controller A, and batteries B for powering the controller and solenoid S, lacking of an actuating valve for manually operating the flush valve. PA0 3. Without implementing any filtering medium in the valve, the dirt or rust may be accumulated on the core of the solenoid S to retard the movement of the core without closing the valve opening V when needed, thereby being unable to stop flushing automatically. PA0 4. Once the solenoid is out of order, the valve opening V is always opened to cause continuous water drainage and waste water resource.
U.S. Pat. No. 5,295,655 to John R. Wilson disclosed a toilet device flush valve having a movable diaphragm closing upon the valve seat to control flow between the inlet and the outlet, having a handle assembly (16) controlling movement of a plunger (18), a relief valve (42) and the diaphragm (32).
However, when it is intended to flush the toilet, the handle (16) should be continuously operated to actuate the plunger (18) to tilt the relief valve (42) for opening the diaphragm (32). Upon releasing of the handle (16), the water will be immediately stopped to interrupt the flushing for the toilet, causing inconvenient flushing operation or even an incomplete cleaning of the toilet.
The present inventor has found the drawbacks of the conventional flush valve and invented the present reliable flush valve.